Studies in the past have shown it: the brains of Neanderthals were the same as those of modern humans. In contrast, scientists know very little about early brain development, because the soft tissues that made them up don’t preserve well in found fossils. But a study published on September 8 could say more about what would have given modern man an advantage, reports CNN.

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An ability to produce more neurons?

According to this study conducted by the Max Planck Institute in Dresden, Germany, which specializes in molecular cell biology and genetics, a genetic mutation would have triggered the creation of neurons more quickly in the brain of sapiens. An amino acid would be the element that differs between the human and Neanderthal variant. “We have detected a gene that contributes to making us human”, revealed the author of the study, and professor emeritus of the institute, Wieland Huttner. The scientists did analyzes on mice and found that inserting the gene in question increased the proportion of specific cells that create neurons in the neocortex region of the brain.

This ability to produce more neurons arguably gave sapiens a cognitive advantage regardless of brain size. “This shows that even though we don’t know how many neurons the Neanderthal brain was made up of, we can assume that modern humans have more neurons in the frontal lobe of the brain,” Wieland Huttner said. Scientists wondered if the Neanderthals’ frontal lobe was as large as humans, but ultimately the question was begged, as modern humans have more neurons in the frontal lobe.

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“Dramatic differences” on a cell line

Professor at the University of California, San Diego, and director of the stem cell program and the center of Archeology, Alysson Muotri explains that “quite dramatic” differences were noted during animal tests, but that they were more subtle in organoids. He also points out that it would be useful to do this experiment in another cell line, which is why, according to him, it is “premature to note differences between Neanderthals and modern humans”.

Study Reveals Striking Differences Between Our Brains and Neanderthals

New research suggests that a mutation stimulating the growth of neurons in our neocortex may be responsible for our superior cognitive abilities compared to Neanderthals.

THE TKTL1 PROTEIN

The mutation in question leads to a single amino acid change in a protein called TKTL1. Previous studies have shown that this mutation is present in almost everyone living todaybut not in older humans, such as Neanderthals and the Denisovansnor in other primates.

The TKTL1 protein is also known to be produced in progenitor cells that give rise to the neocortex (the outer layer of the brain involved in conscious thought and language). suggesting that she may have helped shape the brain modern humans, in particular by increasing the synthesis of certain membrane molecules necessary to increase the production of neurons in the frontal lobe.

As part of work published in the journal Science, Anneline Pinson and her colleagues at the Max Planck Institute sought to precisely determine its impact, by injecting the modern human TKTL1 protein into the brains of mouse embryos and ferrets. They also cultured brain organoids from human cells, some of which were modified to produce the older version of TKTL1, present in Neanderthals.

These experiments showed that the mutation increased the number of neocortical progenitor cells, called radial basal glia, involving a higher number of neurons in this part of the brain. According to Wieland Huttner, co-author of the study, the result would have been “an increase in the size of the neocortex, the density of neurons inside, or even both”.

SKULLS OF A SIMILAR SIZE BUT DIFFERENT SHAPE

The study of the skulls suggests that the brains of modern humans and Neanderthals were similar in size, but different in shape, with Neanderthals having more elongated brains. According to the researchers, it is possible that this difference in shape is also due to the mutation.

“Even though we don’t know how many neurons the Neanderthal brain had, we can assume that the frontal lobe of modern humans, where TKTL1 activity is highest, harbors more of them,” Pinson points out.

So could we make people smarter by modifying genes to increase the number of basal radial glial cells? “I don’t know if we could do it,” says the researcher. “Having more neurons can also have disadvantages. »

Why have modern human brains stopped growing?

In the collective imagination, as in science fiction, an oversized skull and brain is a sign of extraordinary cognitive abilities. This is what happened in human history: among hominins, our ancestors, there was an increase in brain size over time. This is the case for us, the Sapiens, but also for the Neanderthals, whose brain is sometimes larger than that of modern humans. Above all, our brains have not increased in size in the last 300,000 years. How did it grow and improve without increasing in size?

To answer this question, the researchers studied gene variants, gene versions involved in brain development and which are different in Neanderthals and modern humans, in particular that of the TK-TL1 gene. The scientists used organoids, tiny laboratory brains into which different versions of a gene could be implanted. It turns out that the Sapiens version produces more neurons and more connectivity between neurons… in the neocortex of the frontal lobe than the Neanderthal version! And we know that this frontal lobe is decisive for certain cognitive abilities such as language, decision-making or creativity. The modern human, Sapiens, would therefore have followed another path of improvement than the endless increase in brain size.

Neanderthals disappeared 40,000 years ago, but thanks to their DNA they are still among us

They were very successful and spread in an area from the Mediterranean to Siberia. They hunted big game, gathered plants, gathered mushrooms and seafood, controlled fire for cooking, made composite tools, made clothing from animal skins, made beads from shells, and engraved symbols on the walls of caves. They cared for their young, old, and sick, created shelters for protection, lived through harsh winters and hot summers, and buried their dead.

Neanderthals encountered our ancestors many times over tens of thousands of years, and the two species shared the continent of Europe for at least 14,000 years. They even mated. The most significant difference between Neanderthals and us is that they died out around 40,000 years ago.

The precise cause of their disappearance still eludes us, but we believe it is likely the result of a combination of factors. First of all, the climate of the last ice age was very variable, going from cold to hot and vice versa, which put pressure on animal and plant food sources.

Then, there have never been so many Neanderthals, the global population never exceeding tens of thousands of individuals.

They lived in groups of 5 to 15 individuals, while Sapiens had up to 150 individuals. Finally, there was competition, especially with the groups of modern humans who emerged from Africa around 60,000 years ago. We assume that many Neanderthals may have been assimilated to the larger bands of sapiens.

Neanderthals have left many traces for us to examine tens of thousands of years later. Over the past 150 years, we’ve collected fossil bones, stone and wooden tools, found artifacts and jewelry they left behind, uncovered burials, and now mapped their genome from DNA.

It turns out that many Europeans and Asians have between 1% and 4% Neanderthal DNA while Africans south of the Sahara have almost zero. Ironically, with a current world population of around 8 billion people, this means there has never been so much Neanderthal DNA on Earth.

The Neanderthal genome also helps us better understand what they looked like, as there is evidence that some Neanderthals developed pale skin and red hair long before sapiens. The many genes shared between Neanderthals and modern humans are linked to everything from the ability to taste bitter foods to the ability to speak.

We have also improved our knowledge of human health. For example, some Neanderthal DNA that might have benefited humans tens of thousands of years ago now appears to cause problems when combined with a modern Western lifestyle.

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